Cent Eur J Public Health 2009; 17 (3): 115–121
SOCIOECONOMIC INDICATORS AND RISK OF LUNG CANCER IN CENTRAL AND EASTERN EUROPE Františka Hrubá1, Eleonóra Fabiánová1, Vladimír Bencko2, Adrian Cassidy3, Jolanta Lissowska4, Dana Mates5, Péter Rudnai6, David Zaridze7, Lenka Foretová8, Vladimír Janout9, Neonilia Szeszenia-Dabrowska10, Paul Brennan11, Paolo Boffetta11 Regional Authority of Public Health, Banska Bystrica, Slovakia Institute of Hygiene and Epidemiology, First Faculty of Medicine, Charles University, Prague, Czech Republic 3 Roy Castle Lung Cancer Research Programme, University of Liverpool Cancer Research Centre, University of Liverpool, United Kingdom 4 Cancer Center and M.Sklodowska-Currie Institute of Oncology, Warsaw, Poland 5 Institute of Public Health, Bucharest, Romania 6 National Institute of Environmental Health, Budapest, Hungary 7 Cancer Research Centre, Moscow, Russia 8 Masaryk Memorial Cancer Institute, Brno, Czech Republic 9 Faculty of Medicine, Palacky University, Olomouc, Czech Republic 10 Institute of Occupational Medicine, Lodz, Poland 11 International Agency for Research on Cancer, Lyon, France 1 2
SUMMARY Background: Social inequalities have been shown to contribute to the risk of lung cancer in industrialized countries, but it is unclear whether they also play a role in former socialist countries of Europe. Methods: A case-control study involving 3,403 cases and 3,670 controls was conducted in Central European countries (Czech Republic, Hungary, Poland, Romania, Slovakia), Russia, and in the UK. Indicators of socioeconomic status, including education and white/blue collar occupation based on lifetime occupations were analysed as indicators of risk factors for lung cancer development, after adjustment for tobacco smoking and exposure to occupational carcinogens. Results: Both indicators of socioeconomic status: low education and blue collar occupations were found as significant risk factors for lung cancer in men. The odds ratio of lung cancer for blue collar occupations compared to white collar occupations was 1.37 (95% confidence interval 1.15–1.62), that for low education compared to high education (analysis restricted to Central European countries) was 1.35 (95% confidence interval 1.03–1.77). No such effects were observed in women. Conclusions: The confirmation of the significant inverse association between the indicators of socioeconomic status and lung cancer risk in men may serve as a strong incentive for adoption of occupational and public health measures in lung cancer prevention.
Key words: lung cancer, socioeconomic status, indicators, white/ blue collar occupation, education Address for correspondence: F. Hrubá, Regional Authority of Public Health, Cesta k nemocnici 1, 975 56 Banská Bystrica, Slovakia. E-mail:
[email protected]
INTRODUCTION In the former socialist Central European countries, many common diseases remain more prevalent than in the developed industrialized countries – cardiovascular diseases, cancer in general and lung cancer in particular. Cancer of the trachea, bronchus and lung is a major component of cancer mortality (1). The cumulative risk of developing lung cancer in these countries is among the highest in the world, being currently around 10% among men by the age of 75 (2). In industrialized countries, male lung cancer risk shows a negative gradient by socioeconomic status, particularly in recent decades. A systematic review reported a negative mortality trend in 34 male populations compared with 6 positive trends, and paral-
leled by 13 negative gradients in incidence (3). Since time of the review, other studies confirmed this gradient as well (4–11). In women, the patterns are less consistent (3, 8–10). Little is known on the social class effect in former socialist countries. The goal of this article is to investigate association between two available indicators of socioeconomic status (education and white/blue collar occupation) and risk of lung cancer development in seven European countries, including five former socialist countries from Central Europe and Russia. Main hypothesis is, that higher lung cancer risk is associated with low education and blue collar occupations. The investigation takes into account the two factors which may be responsible for the effect of socioeconomic status indicators on lung cancer risk: tobacco smoking and exposure to occupational carcinogens (4, 9, 12, 13).
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MATERIAL AND METHODS A hospital based case-control study was conducted in 16 areas of seven countries: Brno, Olomouc, and Prague (Czech Republic), Borsod, Budapest, Heves, Szabolcs, and Szolnok (Hungary), Lodz, and Warsaw (Poland), Bucharest (Romania), Moscow (Russia), Banska Bystrica, Bratislava, and Nitra (Slovakia), Liverpool (United Kingdom). In each area, newly diagnosed, histologically or cytologically confirmed cases of primary lung cancer were recruited during 1998–2001 together with controls frequency-matched by sex and age. The selection criteria for cases were residence in the study area for at least one year prior to diagnosis, and age lower than 75. Hospital based controls were selected in most centres among patients admitted to the same hospitals of the cases or general hospitals serving the study areas for diseases other than cancer or tobacco-related. In Liverpool and Warsaw, population based controls were selected from population or general practitioner registries. Both cases and controls were interviewed using a standardized questionnaire which consisted of questions about residential history, tobacco smoking, diet, medical history, as well as occupational history. The latter included collection of detailed information on each job held by study subjects in a chronological order, which was used to assess exposure to 70 known and potential occupational lung carcinogens. For the socioeconomic status, two indicators of socioeconomic status were studied: an occupation-based classification, and education. The occupation-based indicator was derived from the
Annex 1: Construction of the occupation-based indicator of socioeconomic status by ISCO code from 1968 ISCO code
Description
White collar 0,1
Professional, technical and related workers
2
Administrative and managerial workers
3
Technical, health, pedagogical workers
4.0–4.4
Clerical and related workers
5.0
Managers (sales and services)
6.0
Farm managers and supervisors
7.0
Production supervisors
Blue collar 4.5–4.9 5.1–5.9 6.1–6.4 7.1–7.9, 8, 9
lifetime occupational history, where ISCO codes from 1968 (14) were used to distinguish between white and blue collar occupations, and to record an inactive period for each individual job. Professional, technical, managerial, administrative occupations and property owners were categorized as white collar jobs. Shopping, services, craft, agriculture and industry manual occupations were categorized as blue collar jobs. Military service, retirement, study, household, long-term disablement, and arrest were taken as the inactive periods (Annex 1). Overall, study participants with employment in blue collar occupations for more than two thirds of their total occupational history (ignoring inactive periods) were categorized as blue collar workers (and similarly white collar workers). The remaining study participants were treated as a mixed group. Education was classified in three categories: low (up to completion of elementary school), middle (apprentice and secondary school) and high (higher than secondary school). Odds ratios (OR) for risk of lung cancer development and 95% confidence intervals (CI) were derived from unconditional logistic regression models. All models were fitted separately for men and women, because previous studies had indicated different association between socioeconomic status and lung cancer according to gender (13). In the analysis by education, data from Liverpool were excluded, due to very different education system in the United Kingdom as compared to Central European countries. Regression models included country, age (4 categories: less than 50, 50–59, 60–69, 70 and more), tobacco smoking and occupational exposure to carcinogens. Tobacco smoking variables represented a cumulative tobacco consumption expressed as pack years (1 pack year is defined as 20 manufactured cigarettes smoked per day for 1 year) in categories (0, 18 & packyears ≤33
Pack-years >33
White collar
28.6
26.2
22.8
22.4
61.7
21.0
11.5
5.8
Mixed group
25.8
23.3
19.5
31.4
47.4
29.8
14.0
8.8
20.3
22.4
26.0
31.3
65.3
16.2
12.0
6.5
Occupation
Blue collar p-value
